The present invention relates to a novel class of cationic dye-borate anion complexes which are capable of absorbing actinic radiation and producing free radicals which can initiate polymerization or crosslinking of free radical polymerizable or crosslinkable compounds. These cationic dye-borate anion complexes are useful as photoinitiators and in photohardenable compositions and photosensitive materials containing the same.
U.S. Pat. Nos. 4,772,541 and 4,772,530 to The Mead Corporation disclose a novel class of photoinitiators which are compounds consisting of an ionic photoreducible or photooxidizable dye and a counter ion which absorb light and generate a free radical. The preferred photoinitiators are complexes of a cationic dye and an alkyltriaryl borate anion. While these photoinitiators are suitable for many applications there is a desire to design photoinitiators which provide higher film speeds.